The militant group behind the four-day takeover of a Nairobi mall claim Kenyan government forces used explosives in carrying out "a demolition" of the building, burying 137 hostages.

Smoke rises from Westgate Mall, site of hostage seige in Kenya (Twitter)

In a Tweet Wednesday from an account believed to be genuine, al-Shabab also claimed that "having failed to defeat the mujahideen inside the mall, the Kenyan govt disseminated chemical gases to end the siege."

 

Government spokesman Manoah Esipisu immediately denied the claim, saying that no chemical weapons were used and that the official civilian death toll remains 61. He says three floors of the building collapsed after a fire started by the al-Shabab attackers caused structural weakness.

 

Kenya's president has declared an end to a four-day siege on a Nairobi mall by Islamic militants.

gunshots from the shopping center continue to ring out. A government spokesman says the shots were fired by Kenyan forces going through the building.

Meanwhile, Kenyans have begun three days of mourning for the dozens of people killed in the attack.

And officials say there are many bodies still in the building, which is now partially collapsed.

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